In 1973, a presidential commission issued a report that suggested the installation of fire sprinkler systems in all residential buildings to reduce fire-related deaths. Today, fire marshalls across America are beginning to require residential sprinkler systems in apartments, duplex homes, and other buildings to protect both fire and property. The installation of such systems is particularly important in multiunit structures, where a fire may begin in one residence and pass quickly to another due to the adjoining structure. However, in any densely populated area, a large fire may spread from home to home, and in sparsely populated areas, the distribution or lack of adequate fire fighting equipment may increase the hazards and losses should a fire become started. Thus, residential sprinkler systems are desirable in all types of residential buildings.
The installation of residential sprinkler systems also saves money. Many insurance companies offer lower rates for homes having installed sprinkler systems, particularly for larger homes in those rural areas that have substandard fire fighting ability. In such cases, a fire sprinkler system will recover its cost in less than two years. In cities, city engineers can allow developers to install smaller fire lines and plugs if fire sprinkler systems are installed in residential housing, thus lowering the construction cost of the entire neighborhood.
However, the use of residential lines for fire protection is not completely devoid of concerns for utility companies. Utility companies will be held accountable if any utility owned product restricts water flow to a fire protection sprinkler system. On the other hand, these same companies are under pressure to meter and bill all water lines in order to increase revenue and decrease losses caused by unmetered water. Prior art meters that are used in conventional ways to meter water are vulnerable to blockages should, for example, a small stone become lodged in the measuring chamber of the meter. In such a case, the water flow stops just as though a valve was shut. As can readily be appreciated, the consequences of such a blockage in a fire sprinkler system can be serious or even catastrophic.
The NFPA (National Fire Protection Association) promulgates standards for residential fire lines in NFPA 13R, which is adopted as a regulation in most areas in the United States. This standard requires residential fire lines to provide 13 gallons per minute (gpm) to 4 sprinkler heads, or a total of 52 gpm, which typically is met through the installation of 1" (one inch) fire lines. Utility companies presently have two alternatives to prevent the unmetered flow of water through these fire lines--water flow detectors and 1" positive displacement meters. Water flow detectors are devices that alarm the fire department when a flow is detected, which may indicate either the start of a fire or the use of unmetered water. Their cost is justified in low volume commercial applications, but the devices can become costly in high volume residential neighborhoods and unruly because of false alarms. However, most utility companies are installing 1" positive displacement meters to record consumption up to 52 gpm instead of a water flow detector. These meters may be subject to blockage in critical situations.
It would thus be advantageous to provide a residential fire service metering device and method that can retrofit existing 1" (and other size) fire lines, and that avoids flow blockages caused by debris. Such a metering device and method should also have low head loss to prevent flow reduction, be able to (at least) register flow if a home owner taps into a fire line and meter water sufficiently accurately at high flow rates to avoid giving away large amounts of free water, and be reasonably priced for large volume residential applications.